Hot-gas piston engines



Y 1967 H. c; J. BEUKERING ETAL 3,318,089

HOT-GAS PISTON ENGINES Filed Sept. 2, 1965 4 SheetsSheet l FIG.1

INVENTORJ HENRICUS C.J.BEUKERING AUGUST A. LIEBE y 1967 H. c. J. BEUKERING ETAL 3,318,089

HOT-GAS PISTON ENGINES Filed Sept. 2, 1965 4 Sheets-Sheet '2 INVENTORS HENRICUS CJ BEUKERING AUGUST A. LIEBE BY w AGEN;

y 1967 H. c. J. BEUKERING ETAL 3,318,089

HOT -GAS PISTON ENGINES 4 SheetsSheet 5 Filed Sept. 2, 1965 INVENTORS HENRICUS C.J.BEUKERING AUGUST A. user:

BY W P.

AGENT y 1967 H. c. J. BEUKERING ETAL. 3,318,089

HOT-GAS PISTON ENGINES Filed Sept. 2, 1965 70 4 Sheets-Sheet 4 FIG. 6

INVENTOR!) HENRICU S C.J.BEUKER|NG AUGUST A. LIEBE BY M K.

AGENT United States Patent 3,318,089 HOT-GAS PISTON ENGINES Henricus Cornelis Johannes Beukering and August Albert Liebe, both of Emmasingel, Eindhoven, Netherlands, assignors to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Sept. 2, 1965, Ser. No. 484,660 Claims priority, application Netherlands, Sept. 10, 1964, 6,410,513 4 Claims. (Cl. 6024) This invention relates to hot-gas piston engines of the displacer type comprising two identical cranks located one on each side of a plane passing through the centre line of the engine, which cranks form parts of two crank shafts which can rotate synchronously and at least substantially in phase and in opposite directions and the centre lines of which lie in parallel on each side of the said plane through the centre line of the engine, each connection between the piston and the displacer respectively and a crank on a crank shaft including a piston connecting rod and a. displacer connecting rod respectively, which piston connecting rods and displacer connecting rods respectively have substantially the same length, one end of each piston connecting rod being secured to a yoke to which the piston rod is connected and one end of each displacer connecting rod being secured to a further yoke to which the displacer rod is connected, the yokes being located one on each side of the plane passing through the centre lines of the crank shafts.

In known hotgas piston engines of the said type, which are to be understood to mean hot-gas piston engines, cold-gas refrigerators as well as heat-pumps, the latter two operating on the so-called reverse hot-gas motor principle, the piston rod and the displacer rod are rigidly coupled to their associated yokes. In this construction, which is statically undefined, very stringest requirements are imposed upon the accuracy of manufacture and assembly of the driving mechanism. Due to the rigid yokerod connection, impermissibly great forces occur between the piston and the wall of the cylinder and in the pivots of the driving mechanism even with small deviations, for example, in the mutual lengths of the piston connecting rods or of the displacer connecting rods. Also a small undesirable phase difference between the cranks may already cause the said disadvantage.

An object of the invention is to provide a hot-gas piston engine in which this disadvantage is avoided and in which the requirements of manufacture and assembly can also be less stringent, which is an important advantage especially in the manufacture and assembly in bulk. According to the invention, to this end, the connection be tween at least one yoke and the associated piston rod or displacer rod is formed by a pivotal coupling the centre line of which extends in parallel with the centre lines of the crank shafts.

Due to the pivotal suspension, the construction obtained is defined statically. The yoke will invariably adjust itself so that the centre line of the pivot moves along the centre line of the piston rod or displacer rod, whilst also a rotational movement of the yoke is permissible without causing impermissible forces in the driving mechanism. The present invention underlies recognition of the fact that for complete suppression of the difificulties set out it suflices to make the coupled parts pivotable in the above-mentioned direction. Such a coupling may readily be obtained.

The piston rod and the displacer rod may be formed with, for example, two projections which are supported in apertures in the yoke. However, the manufacture of the rod is in this case complicated. In one preferred embodiment of the invention the pivotal coupling includes a tilting pin having a bore through which the associated rod passes, which tilting pin is rigidly connected to the rod and pivotally supported in a bore in the yoke, which lies parallel to the centre lines of the crank shafts. The pivotal coupling between the two parts to be coupled is thus obtained in a structurally simple manner.

In another embodiment an advantageous pivotal action is obtained if, according to the invention, the piston rod and the displacer rod respectively have a thickened head which lies between two walls of the yoke, both the walls of the yoke and the head of the rod having bores which are located in alignment and parallel to the centre lines through the crank shafts, in which bores a tilting pin is arranged so as to be pivotal in at least one bore.

This embodiment is preferably suitable for use in a hot-gas piston engine in which the seal between the piston rod and the displacer rod passed through the piston rod is formed by a rolling diaphragm and in which the space located at the side of the rolling diaphragm which is remote from the working space is filled with liquid, the displacer rod being tightly surrounded by a sleeve which is accommodated in a sealing manner in a recess of the piston rod and a system of forces applying to that end of the sleeve which is adjacent the space filled with liquid. In this engine, which is known per se, the rolling diaphragm seals the working space, which is under pressure, from the annular space between the piston rod and the displacer rod. The sleeve acts in known manner as a hydraulic pump which provides the side of the rolling diaphragm which is remote from the working space with the necessary hydraulic counter-pressure. Forced lubrication of the pivotal parts of the tilting pin and of the piston rod may be obtained in a simple manner and without using additional expedients if, according to the invention, the tilting pin connecting the piston rod and the piston yoke lies between the area at which the rolling diaphragm is connected to the piston rod and the area at which the sleeve co-acts with the displacer rod, seals being provided between the bore in the piston rod and the tilting pin pivotally supported therein, which seals lie near the ends of the tilting pin.

In order that the invention may be readily carried into effect, it will now be described in detail, by way of eX- ample, with reference to the accompanying diagrammatic drawings, in which:

FIGURE 1 shows a hot-gas piston engine in which the piston and displacer rods are pivotally connected to their associated yokes;

FIGURE 2 shows the connection of the piston rod to the piston yoke on a larger scale;

FIGURE 3 is a sectional view, taken on the line III-lII of FIGURE 2;

FIGURE 4 shows a further form of the connection between the piston rod and the yoke;

FIGURE 5 is a sectional view taken on the line V-V of FIGURE 4, and

FIGURE 6 shows a portion of a hot-gas piston engine having a lubricating system for the pivotal connection.

In FIGURE 1 the reference numeral 1 indicates a cylinder of a hot-gas piston engine in which a displacer 2 and a piston 3 can move to and fro with phase displacement. The upper end of the cylinder is formed by a cylinder head 4 having internal fins 5 and external fins 6. A lining 7 separates the fins 5 and the regenerator 8 from the inner side of the cylinder. The cylinder 1 also has holes 9 which communicate with a space containing fins 10 secured to a body 11 provided with external ribs 12, which fins and ribs constitute a cooling system. Instead of the ribs 12, the body 11 may be provided with ducts for cooling water. The cylinder head 4 is surrounded by a body 13 which houses a burner 14 shown diagrammatically.

The combustion gases streak along the fins 6 and, after having given off their heat, leave the body 13 through an outlet duct 15. The cylinder head 4 is secured to the body 11 with the aid of threaded bolts 16, the body 11 in turn also being connected to a crank case 18 by means of threaded bolts 17. These bolts also rigidly connect the cylinder 1 to the crank case 18. The piston 3 has a hollow rod 19 the end of which is pivoted to a yoke 20. The yoke also has two pivots 21 which are each pivotally secured to one thickened end of each of the pistonconnecting rods 22. A displacer rod 23 secured to the displacer 2 passes through the piston rod 19. The connecting rods 22 also have heads 24 which can rotate about crank pins 25. The crank pins 25 are secured to cranks 26 connected to crank shafts 27. The cranks 26 also carry crank pins 28 which are surrounded by heads 29 of connecting rods 30. The other ends of the connecting rods 30 are provided with heads which are rotatably secured to pivots 32 located in a yoke 33 to which the displacer rod 23 is also pivoted with the aid of a pin 35. The crank shafts 27 are coupled together by means of intermeshing gear wheels 34 which are rigidly fitted on the said shafts.

In this embodiment of the hot-gas piston engine the crank case 18 has a partition 37 which separates a space 38 from the space containing the driving mechanism. The space 38 communicates freely through apertures 39 with the space below the piston and is also filled with working medium. The piston rod 19 and the displacer rod 23 are coupled to the driving mechanism through an aperture 40 in the partition. Inside the aperture 40 the piston rod 19 is surrounded by a gas-tight seal 41, and such a gass-tight seal also exists between the piston rod 19 and the displacer rod 23. It will be evident that the space containing the driving mechanism need not be gastight and that a pressure corresponding to atmospheric pressure can adjust itself in the said space.

The yoke 20 comprises a block (FIGURES 2 and 3) having a bore 43 through which the piston rod 19 passes. The yoke 20 has a second bore 44 which lies parallel to the centre lines through the crank shafts 27. Supported in the bore 44 is a tilting pin 45 which in turn has a bore 46 through which the end of the piston rod 19 passes. The tilting pin 45 is secured on the threaded end of the piston rod with the aid of a nut 47. The bore 43 in the yoke 20 has a diameter such that the yoke can pivot about the tilting pin relative to the piston rod.

In this embodiment the piston rod 19 may have a very simple form, the surface pressure on the tilting pin is low because of the large supporting surface, and assembling and dismantling is simple.

The connection between the displacer rod 23 and the yoke 33 may be similar to that shown for the piston rod 19. However, it is not invariably necessary for the displacer yoke to be pivoted to the displacer rod. The displacer rod 23 is frequently made fairly long and thin and, since it is then fairly slack, it can neutralize deformation more readily without harmful consequences.

FIGURES 4 and 5 show another embodiment of a yoke as used in the hot-gas piston engine according to the invention. The yoke 50 in this case comprises two links 51. The pivots 21 to which the piston connecting rods 22 are rotatably connected are fished on the links 51, for example, by means of contraction. The end of the piston rod 19 has a thickened head provided with a bore 52 through which a tilting pin 53 passes. The tilting pin 53 is shrinked in a bore 54 on each link 51 and lies again parallel to the centre lines through the crank shafts. The tilting pin 53' may be locked against axial displacement and rotation by means of locking plates 55. The tilting pin has a further bore 56 through which the displacer rod 23 passes.

In the embodiment shown, the tilting pin 53 is rigidly connected to the links 51, the piston rod 19 being pivotal relative to the tilting pin. However, it is also possible rigidly to shrink the piston rod on the tilting pin and pivotally to support the tilting pin in the links, or to make both the piston rod and the links pivotal relative to the tilting pin.

The embodiment of FIGURES 4 and 5 is very suitable for use in a hot-gas piston engine as shown in part in FIGURE 6. A seal in the form of a rolling diaphragm 60 is arranged between the piston 3 and the displacer rod 23. The displacer rod 23 passes through the piston rod 19. The rolling diaphragm 60 separates the space above the piston from a space 61 between the piston 3 and the displacer rod 23. Further a rolling diaphragm 62 is shown which seals the piston 3 from the cylinder 1.

A cavity 64 provided at the lower end of the piston rod 19 houses a sleeve 65 of substantially rectangular cross-section which is supported on its rear side by an elastic O-ring 66. The sleeve is made, for example, of White metal and its inner surface engages the outer surface of the displacer rod 23 without clearance. The sleeve 65 is subject to a system of forces originating from a plurality of rigid springs 67 which apply to a thinner portion 68. The springs 67 are fitted on a ring 69 which is secured to the upper surface of the cavity 64 with the aid of means not shown.

Normally, lubricating oil is present on that portion of the displacer rod 23 which projects from the piston rod 19. The sleeve 65 acts in known manner as a pump. During the upward stroke of the displacer rod 23, a wedgeshaped gap which passes oil upwards is formed as a result of the increasing pressure in the lubricating oil present between the sleeve 65 and the displacer rod 23. During the downward stroke, this possibility of deformation of the sleeve 65 does not exist or hardly exists due to the force exerted on the sleeve by the springs 67. Consequently the sleeve pumps oil upwards. This oil acts upon the rolling diaphragm 6t constituting a counterforce for the working pressure above the piston 3 which prevails at the other side of the rolling diaphragm.

The space in the cylinder communicates through a line 70 with a control valve 71 which houses a diaphragm 72. A duct 73 connects the space 61 filled with liquid, below the rolling diaphragms 60 and 62 to the control valve 71 which has an outlet duct 74 for oil. The diaphragm 72 and the outlet duct 74 together constitute a valve. The control valve 71 maintains in known manner a constant pressure difference between the spaces above the rolling diaphragm 60 and the space 61 below it.

By arranging the pumping sleeve 65 below the pivotal connection between the yoke 50' and the piston rod 23, the tilting pin 53 lies on the compression side of the pumping circuit and is thus lubricated in a forced manner by the liquid being pumped up, which is normally lubricating oil. Between the bore 52 in piston rod 19 and the tilting pin 53 there are provided two O-rings which prevent leakage of oil along the yoke 50.

What is claimed is:

1. A hot-gas piston engine of the displacer type comprising two identical cranks located one on each side of a plane passing through the center line of the engine, which cranks form parts of two crank shafts which can rotate synchronously and at least substantially in phase and in opposite directions and the center lines of which lie in parallel on each side of the said plane through the center line of the engine, each connection between a piston and a displacer respectively and a crank on a crank shaft including a piston connecting rod and a displacer connecting rod respectively which piston connecting rods and displacer connecting rods respectively have substantially the same length, one end of each piston connecting rod being secured to a yoke to which the piston rod is connected and one end of each displacer connecting rod being secured to a further yoke to which the displacer rod is connected, the yokes being located one on each side of the plane passing through the center lines of the crank shafts, characterized in that the connection between at 5 least one yoke and the associated piston rod or displacer rod is formed by a pivotal coupling the center line of which extends in parallel with the center lines of the crank shafts.

2. A hot-gas piston engine as claimed in claim 1, characterized in that the pivotal coupling includes a tilting pin having a bore through which the associated rod passes, which tilting pin is rigidly connected to the rod and pivotally supported in a bore in the yoke which lies parallel to the center lines through the crank shafts.

3. A hot-gas piston engine as claimed in claim 1, characterized in that the piston rod and the displacer rod respectively have a thickened head located between two walls of the yoke, both the walls of the yoke and the head of the rod having bores located in alignment and parallel to the center lines of the crank shafts, in which bores a tilting pin is arranged so as to be pivotal in at least one bore.

4. A hot-gas piston engine as claimed in claim 3, in which the seal between the piston rod and the displacer rod which passes through the piston rod is formed by a rolling diaphragm and in which the space located at the side of the rolling diaphragm remote from the working space is filled with liquid, the displacer rod being tightly surrounded by a sleeve which is accommodated in a sealing manner in a recess of the piston rod, and a system of forces applying to that end of the sleeve which is adjacent the space filled with liquid, characterized in that the tilting pin connecting the piston rod to the piston yoke lies between the area at which the rolling diaphragm is connected to the piston rod and the area at which the sleeve co-acts with the displacer rod, seals being provided between the bore in the piston rod and the tilting pin pivotally supported therein, which seals are located near the ends of the tilting pin.

References Cited by the Examiner UNITED STATES PATENTS 2,885,855 5/1959 Mayer 60-24 3,062,000 11/1962 Percival 6024 X 3,220,177 11/1965 Kohler 6024 EDGAR W. GEOGHEGAN, Primary Examiner. 

1. A HOT-GAS PISTON ENGINE OF THE DISPLACER TYPE COMPRISING TWO IDENTICAL CRANKS LOCATED ONE ON EACH SIDE OF A PLANE PASSING THROUGH THE CENTER LINE OF THE ENGINE, WHICH CRANKS FORM PARTS OF TWO CRANK SHAFTS WHICH CAN ROTATE SYNCHRONOUSLY AND AT LEAST SUBSTANTIALLY IN PHASE AND IN OPPOSITE DIRECTIONS AND THE CENTER LINES OF WHICH LIE IN PARALLEL ON EACH SIDE OF THE SAID PLANE THROUGH THE CENTER LINE OF THE ENGINE, EACH CONNECTION BETWEEN A PISTON AND A DISPLACER RESPECTIVELY AND A CRANK ON A CRANK SHAFT INCLUDING A PISTON CONNECTING ROD AND A DISPLACER CONNECTING ROD RESPECTIVELY WHICH PISTON CONNECTING RODS AND DISPLACER CONNECTING RODS RESPECTIVELY HAVE SUBSTANTIALLY THE SAME LENGTH, ONE END OF EACH PISTON CONNECTING ROD BEING SECURED TO A YOKE TO WHICH THE PISTON ROD IS CONNECTED AND ONE END OF EACH DISPLACER CONNECTING ROD BEING SECURED TO A FURTHER YOKE TO WHICH THE DISPLACER ROD IS CONNECTED, THE YOKES BEING LOCATED ONE ON EACH SIDE OF THE PLANE PASSING THROUGH THE CENTER LINES OF THE CRANK SHAFTS, CHARACTERIZED IN THAT THE CONNECTION BETWEEN AT LEAST ONE YOKE AND THE ASSOCIATED PISTON ROD OR DISPLACER ROD IS FORMED BY A PIVOTAL COUPLING THE CENTER LINE OF WHICH EXTENDS IN PARALLEL WITH THE CENTER LINES OF THE CRANK SHAFTS. 